Fiber-reinforced composite structures provide several advantages over metallic structures. For example, composite structures can be configured to provide high specific stiffness and high specific strength relative to metallic structures. Furthermore, composite structures can be tailored to provide a relatively high degree of strength and stiffness along a primary load path. The ability to tailor the strength and stiffness of composites may result in lightweight structures. In addition, composite materials may have improved fatigue resistance relative to metallic materials and may be more resistant to corrosion.
Composite structures may be formed as a laminate of relatively thin layers or plies that are laminated together. Each ply in the composite laminate may include fibers that serve as the primary load-carrying constituent. Each composite ply may be formed of unidirectional tape wherein the fibers in each ply are oriented parallel to one another and are held in position by a matrix constituent such as an epoxy resin. The matrix constituent may also redistribute or transfer loads between adjacent fibers. A composite laminate may be configured such that the fibers are oriented to provide the desired strength and stiffness characteristics of the composite structure.
Traditionally, composite laminates are composed of plies with fiber angles oriented at 0 degrees, ±45 degrees, and 90 degrees relative to the primary load direction of the composite laminate. Conventional methods of designing composite laminates focus on adjusting the individual ply thickness and fiber angle, and the relative location of each ply in the through-thickness direction to define a ply stacking sequence that meets the strength, stiffness, weight, and manufacturing requirements of the composite laminate. For certain structures, loading conditions may dictate a composite laminate requiring a relatively large quantity of plies. For example, a wing panel of an aircraft may require up to one hundred or more composite plies, each of which requires the determination of the fiber angle and the thickness. As may be appreciated, a ply-by-ply determination of the stacking sequence of relatively thick composite laminates involves a large quantity of design variables which significantly increases the complexity of the design process.
A further drawback associated with conventional methods of designing composite laminates is that the focus on individual fiber angle and ply thickness of conventional design methods makes it difficult to design multi-layered composite structures that contain plies having non-traditional or varying fibers angles. Composite laminates containing plies with fibers oriented at angles other than the traditional 0 degrees, ±45 degrees, and/or 90 degrees may be referred to as non-traditional laminates. Composite laminates containing plies with fibers that curve within the plane of each ply may be referred to as steered fiber laminates. The ability to tailor the fiber angle within the plane of each ply allows for a significant improvement in the structural efficiency of composite laminates. For example, a non-traditional laminate or a steered fiber laminate may have improved strength and/or stiffness characteristics relative to a traditional laminate of the same thickness. Unfortunately, determining the fiber angle of each ply of a relatively thick non-traditional laminate or steered fiber laminate using conventional design methods involves a large quantity of design variables which results in a computationally expensive design process.
As can be seen, there exists a need in the art for a computationally efficient system and method for designing and optimizing composite laminates.